A Transfusion Medicine/Hemostasis Clinical Trial Site to be located at the Puget Sound Blood Center (PSBC) is proposed. PSBC is a regional blood program that distributes all blood and blood products to patients in Seattle and surrounding counties. It is anticipated that network clinical trials will be conducted at any of 6 Seattle hospitals that have a total of 2,193 beds, and, during 2001, 20,996 patients in these hospitals received over 150,000 blood products. Four University of Washington medical school faculty, based at PSBC, with extensive experience in clinical trials will participate with other trial sites in the network clinical trials. These physician scientists are all recognized experts in their areas of research interest; i.e., platelet and granulocyte transfusion therapy, apheresis procedures and their indications, disorders of hemostasis and thrombosis, and patients with ITP. These physicians supervise a hemostasis clinic at PSBC that specializes in hemophilia care, a coagulation laboratory, a platelet antibody laboratory, and an apheresis facility. Through these clinical activities, they are aware of patients with a variety of disorders - besides those in area hospitals - who might be candidates for participation in network clinical trials. Two network clinical trials are proposed: 1) "Evaluate The Hemostatic Efficacy And Platelet Utilization Rates Of Low Versus Standard Dose Platelet Therapy;" and 2) A Multicenter Randomized Controlled Trial On The Efficacy Of Transfusion Of G-CSF Mobilized Granulocytes To Neutropenic Patients With Infection." The first trial seeks to determine whether low dose compared to standard dose platelet transfusions are able to maintain adequate hemostasis while decreasing the total number of platelets required to support thrombocytopenic patients. The primary endpoint will be hemostasis; i.e., to demonstrate non-inferiority of patients randomized to the low dose arm compared to those in the standard close arm in the percentage of patients that develop WHO Grade 2 bleeding. The second trial will evaluate the effectiveness of granulocyte transfusion therapy to determine the clinical efficacy of G-CSF mobilized granulocyte transfusions for neutropenic patients with bacteria or fungal infections. Patients will be randomized to receive daily granulocyte transfusions along with standard care or standard care alone. The primary endpoint will be the proportion of patients in each arm who demonstrate both a microbial response to their infection and who also survive at least 28 days from study entry.